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    Subject[PATCH 4.4 10/22] ACPI: fix false-positive -Wuninitialized warning
    Date
    [ Upstream commit dfd6f9ad36368b8dbd5f5a2b2f0a4705ae69a323 ]

    clang gets confused by an uninitialized variable in what looks
    to it like a never executed code path:

    arch/x86/kernel/acpi/boot.c:618:13: error: variable 'polarity' is uninitialized when used here [-Werror,-Wuninitialized]
    polarity = polarity ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH;
    ^~~~~~~~
    arch/x86/kernel/acpi/boot.c:606:32: note: initialize the variable 'polarity' to silence this warning
    int rc, irq, trigger, polarity;
    ^
    = 0
    arch/x86/kernel/acpi/boot.c:617:12: error: variable 'trigger' is uninitialized when used here [-Werror,-Wuninitialized]
    trigger = trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE;
    ^~~~~~~
    arch/x86/kernel/acpi/boot.c:606:22: note: initialize the variable 'trigger' to silence this warning
    int rc, irq, trigger, polarity;
    ^
    = 0

    This is unfortunately a design decision in clang and won't be fixed.

    Changing the acpi_get_override_irq() macro to an inline function
    reliably avoids the issue.

    Signed-off-by: Arnd Bergmann <arnd@arndb.de>
    Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
    Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    include/linux/acpi.h | 5 ++++-
    1 file changed, 4 insertions(+), 1 deletion(-)

    diff --git a/include/linux/acpi.h b/include/linux/acpi.h
    index 3672893b275ed..6a30f1e03aa9e 100644
    --- a/include/linux/acpi.h
    +++ b/include/linux/acpi.h
    @@ -226,7 +226,10 @@ void acpi_set_irq_model(enum acpi_irq_model_id model,
    #ifdef CONFIG_X86_IO_APIC
    extern int acpi_get_override_irq(u32 gsi, int *trigger, int *polarity);
    #else
    -#define acpi_get_override_irq(gsi, trigger, polarity) (-1)
    +static inline int acpi_get_override_irq(u32 gsi, int *trigger, int *polarity)
    +{
    + return -1;
    +}
    #endif
    /*
    * This function undoes the effect of one call to acpi_register_gsi().
    --
    2.20.1


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